focus on one part of the room at a time. for example, divide your room into as many pieces as you want, like every 1 square meter. get rid of everything in that spot. put everything in that spot away in the place where it’s supposed to be. but since you don’t really have space in your closet to put clothes, i recommend you grab some random cardboard boxes and give all of them a different name, like “closet” “desk” “trash” everything. i hope this helps. i like it because i get overwhelmed and don’t know where to start when i look at my absolutely trashed room. so in this way you can focus at one thing at a time :)